Newbies question?

obito

Im new into the audio stuff. I have no idea what do I need to do. I have read some thread and see that people spend around $700 + to buy and install aftermarket amp+sub into their car. I dont want to spend that much money on audio ,but I just need some bass for hip-hop. the question is do I need to buy a new head unit? I think I saw one thread said If we want to put sub and amp into Z, we need to buy a new head unit because the stock+ converter may not work properly, and head unit itself is about $500+. At that price I would add some more cash into it and get a wing instead, and how much would be the cheapest that I need because I know that one of my friend he just bought sub and amp on his own and then he paid to someone to install it for him, so he ended up like just 300-400 bucks

Ps. I would rather buy JL, Kicker, or Pioneer than cheap sub because my friend said those 3 brands are good.